AKMAK4678 24-bit Stereo CODEC Solution

AKM’s AK4678 is a 24-bit stereo CODEC with built-in microphone amplifier, receiver amplifier, mono class D speaker amplifier, capacitorless class G headphone amplifier and line amplifier. In addition to audio I/F, there are two PCM I/F F. The playback function includes 5-band parametric EQ and dynamic range control, so it can automatically adjust the appropriate volume without distortion. This article introduces the main features of the AK4678, the analog and digital block diagrams, and the evaluation board AKD4678-B function, block diagram, circuit diagram and PCB components Layout.

The AK4678 is a 24bit stereo CODEC with a built-in Microphone-Amplifier, Receiver-Amplifier, Mono Class-D Speaker-Amplifier, Cap-less Class-G Headphone-Amplifier and Line-Amplifier. The AK4678 features dual PCM I/F in addition to audio I/F that allows easy interfacing in mobile phone designs with Bluetooth I/F. The playback features also include 5-band Parametric EQ and Dynamic Range Control, therefore the AK4678 can automatically adjust a comfortable volume without distortion and provides great flexibility. The AK4678 is available in a 49pin CSP, utilizing less board space than competitive offerings.

AK4678 main features:

1. Recording Function (Stereo CODEC)

• 4 Stereo Input Selectors

• 4 Stereo Inputs (Single-ended) or 3 Mono Inputs (Full-differential)

• MIC Amplifier: +24dB ~ −6dB, 3dB step

• 2 Output MIC Power Supplies

• Digital ALC (Automatic Level Control): +36dB ~ −54dB, 0.375dB Step, Mute

• ADC CHARACTERISTICS: S/(N+D): 80dB, DR, S/N: 87dB (MIC-Amp=+18dB) S/(N+D): 80dB, DR, S/N: 92dB (MIC-Amp =0dB)

• Stereo Digital MIC Interface

• Wind-noise Reduction Filter

• Stereo Separation Emphasis

• 3-band Programmable Notch Filter

• Audio Interface Format: 24/16bit MSB justified, 24/16bit I2S, 16bit DSP Mode 2. Playback Function (Stereo CODEC)

• Digital Volume (+6dB ~ −57.0dB, 0.5dB Step, Mute)

• Digital ALC (Automatic Level Control): +36dB ~ −54dB, 0.375dB Step, Mute

• Stereo Separation Emphasis

• Dynamic Range Control

• 5-band Parametric Equalizer

• Stereo Line Output (Selectable Full-differential / Single-ended)

• Mono Receiver-Amp

– BTL Output

– Output Power: 60mW @ 32Ω

– Analog Volume: +12 ~ −30dB & Mute, 3dB Step

• Cap-less Stereo Class-G Headphone-Amp

– Output Power: 25mW @ 32Ω, 45mW @ 16Ω

– Analog Volume: +6 ~ −62dB & Mute, 2dB Step

– Zero crossing Detection

– Pop Noise Free at Power-ON/OFF

• Mono Class-D Speaker-Amp

– BTL Output

– Short Protection Circuit

– Output Power: 1.1W @ 8Ω, SVDD=4.2V, THD+N = 10%

0.89W @ 8Ω, SVDD=4.2V, THD+N = 1%

– Analog Volume: +12 ~ −30dB & Mute, 3dB Step

– Pop Noise Free at Power-ON/OFF

• Audio Interface Format:

– 24/16bit MSB justified, 16bit LSB justified, 16/24bit I2S, 16bit DSP Mode

3. Dual PCM I/F for Baseband & Bluetooth Interface • Four sample Rate Converters (Up sample: up to x6: Down sample: down to x1/6)

• Sample Rate:

– PORTA (Mono): 8 ~ 16kHz

– PORTB (Stereo): 8 ~ 48kHz

• Digital Volume

• Slave Mode

• Audio Interface Format:

– 16bit Linear, 8bit A-law, 8bit μ-law

– Short/Long Frame, I2S, MSB justified

4. Power Management

5. Master Clock (Audio I/F):

(1) PLL Mode

•Frequencies: 11.2896MHz, 12MHz, 12.288MHz, 13MHz, 13.5MHz, 19.2MHz, 24MHz, 25MHz, 26MHz, 27MHz (MCKI pin)

32fs or 64fs (BICK pin)

(2) External Clock Mode

•Frequencies: 256fs, 512fs or 1024fs (MCKI pin)

6. Output Master Clock Frequencies(Audio I/F): 32fs/64fs/128fs/256fs

7. Sampling Frequency (Audio I/F)

•PLL Slave Mode (BICK pin): 8kHz ~ 48kHz

•PLL Master Mode:

8kHz, 11.025kHz, 12kHz, 16kHz, 22.05kHz, 24kHz, 32kHz, 44.1kHz, 48kHz

•EXT Master/Slave Mode:

8kHz ~ 48kHz (256fs), 8kHz ~ 24kHz (512fs), 8kHz ~ 12kHz (1024fs)

8. Audio I/F: Master/Slave mode

9. μP I/F: I2C Bus (Ver 1.0, 400kHz Fast Mode)

10. Ta = −30 ~ 85°C

11. Power Supply:

•SVDD (SPK/RCV/LINE-Amp): 3.0 ~ 5.5V

•AVDD (Analog): 1.7 ~ 2.0V

•DVDD (Digital Core): 1.7 ~ 2.0V

•PVDD (HP-Amp & Charge Pump): 1.7 ~ 2.0V

•TVDD (Digital I/F): 1.6 ~ 3.6V

12. Package : 49pin CSP(2.96 x 2.96 mm, 0.4mm pitch)
AKMAK4678 24-bit Stereo CODEC Solution
Figure 1. AK4678 Analog Block Diagram

Figure 2. AK4678 Digital Block Diagram

Figure 3. AK4678 Typical Connection Diagram (Power Section)

AK4678 Evaluation Board AKD4678-B (Rev.1)

The AKD4678-B is an evaluation board for AK4678, 24bit stereo CODEC with Microphone/Receiver/Headphone/ Speaker/ Line amplifier. The AKD4678-B has the Digital Audio I/F and can achieve the interface with digital audio systems via optical connector.

Evaluation Board AKD4678-B Features:

• DIR/DIT with optical input/output

• 10pin Header for Digital Audio I/F and PCM I/F (Baseband, Bluetooth)

• 10pin Header for I2C control mode

Figure 4. Block Diagram of Evaluation Board AKD4678-B

Figure 5. Evaluation Board AKD4678-B Circuit Diagram (1)

Figure 6. Evaluation Board AKD4678-B Circuit Diagram (2)

Figure 7. Evaluation Board AKD4678-B Circuit Diagram (3)

Figure 8. Evaluation Board AKD4678-B Component Layout
For details, see:

The Links:   LB104S01-TL01 LQ190E1LX77